Science & Mathematics - 13 November 2007

My brother has this thing that is like a light and it is supposed to kill germs. Well, he was waving it over the kitchen counters, and my mom, being silly, said, "Gee, now there will be dead germs all over the kitchen counters!"

But that got me thinking. What DOES happen to dead germs?! Do other germs eat their carcasses? But what if you kill all of them? I know the answer is probably obvious, and this question really shows my stupidity. But I really want to know!

2007-11-13 08:31:10 · 4 answers · asked by Heron By The Sea 7 in Biology

Specifically in the summer and winter.

2007-11-13 08:28:41 · 8 answers · asked by Ashley G 1 in Weather

Which scientist was the first to conclude through experimentation that atoms have positive charges in their nuclei?

2007-11-13 08:24:54 · 1 answers · asked by jo_beanman 1 in Chemistry

1) explain how hydrogen atoms emit radiation? (2)

2)why do hydrogen atoms emit radiation at specific frequencies? (3)

2007-11-13 08:18:24 · 2 answers · asked by Anonymous in Physics

What is the role of hemoglobin in gas transport?
What is one positive role of carbon dioxide in the blood?

2007-11-13 08:15:29 · 2 answers · asked by Zerine 1 in Biology

I am interested in Game theory. Which math classes should I be looking for at the undergrad level. I've already taken precalc.

2007-11-13 08:15:11 · 3 answers · asked by egfraz 2 in Mathematics

I am 80ft from a wall that is 60ft tall. How fast should I throw a rock if I throw it at 60degrees, and I want it to just clear the height of the wall? Can you show your work too please... thanks alot.

2007-11-13 08:13:39 · 2 answers · asked by zachmebay 2 in Physics

You can use a motor, wires switches but it has to go 7 feet and come back 7 feet. No pushing it no pulling it how can u do that?

2007-11-13 08:10:10 · 5 answers · asked by kishen p 2 in Engineering

Tails serve several purposes, the most obvious of which is balance. Since balance is more difficult for bipeds than quadrupeds, it seems like a tail would be particularly useful for bipeds.

Though arms are pretty good for balance, humans like to use their arms for tasks like carrying babies, spears or other weapons, making it more difficult to use arms for balance. Is two million years too short a period to evolve tails?

2007-11-13 08:09:29 · 2 answers · asked by Tom D 4 in Biology

chemistry

2007-11-13 08:09:27 · 1 answers · asked by jo_beanman 1 in Chemistry

What is the probability that their numbers are all greater than 25?

a. 1/8
b. 23/196
c. 69/625
d. 1/2

2007-11-13 08:08:24 · 11 answers · asked by Hollywood614 2 in Mathematics

Just need to find a way to decide that.
Mix the acid with something or whatever!

Thanks.

2007-11-13 08:08:05 · 4 answers · asked by Anonymous in Chemistry

For a class project we have to make a styrofoam boat that is powered by a balloon. What would be the best way to do this?

2007-11-13 08:07:44 · 2 answers · asked by ABC123 4 in Engineering

A. hide
B. Scales
C. Joints
D. Claws

2007-11-13 08:07:22 · 4 answers · asked by achunt 3 in Biology

How would you figure out the engergy flux for a an object with a temperature of 14500 degrees K?

2007-11-13 08:03:20 · 1 answers · asked by gymnast8517 2 in Astronomy & Space

When you push a 1.81 kg book resting on a tabletop, it takes 2.25 N to start the book sliding. Once it is sliding, however, it takes only 1.51 N to keep the book moving with constant speed.

What is the coefficient of static friction between the book and the tabletop?
What is the coefficient of kinetic friction between the book and the tabletop?

I'm trying to approach this problem by:
f(k)=k*N.
f=kmg
k=f/mg
Wrong approach?

2007-11-13 08:03:01 · 2 answers · asked by revernance 3 in Physics

My theory instructor asked us to find this out before the next class. I have a couple theories but am not sure if they are correct. Thanks for the help.

2007-11-13 08:01:56 · 3 answers · asked by Me 3 in Medicine

9. A centimeter is what part of a meter?
1
1/10
1/100
1/1000
unable to determine

10. In chemistry how do we deal with the atomic mass unit (amu)?
substitute grams/mole for amu and round to the nearest tenth decimal place
substitute grams/mole for amu and round to the nearest one decimal place
substitute mole/gram for amu and round to the nearest tenth decimal place
substitute mole/gram for amu and round to the nearest one decimal place

11. Which piece of equipment would you choose to most accurately measure 25.0 ml of water?
a graduated cylinder
a beaker
a thermometer
a test tube

13. What is the density of an object having a mass of 8.0g and a volume of 25cm3?
(*Hint mL = cm3)
0.32 g/cm3
2.0 g/cm3
3.1 g/cm3
200 g/cm3
none of the above

2007-11-13 08:01:28 · 6 answers · asked by emando16 2 in Chemistry

3. Solve with correct significant figures: (3.08 x 10-3) x (4.90 x 10-7) =
1.51x10^10
1.5x10^9
1.5x10^10
1.51x10^9


4. Convert to moles: 3.50 g CaO:
.0625
196
1.75
3.50

5. Mole:
Quantity of a substance (6.02 x 1020) that has units of grams/mole
Quantity of a substance (6.02 x 1043) that has units of grams/mole
Quantity of a substance (6.02 x 1022) that has units of grams/mole
Quantity of a substance (6.02 x 1023) that has units of grams/mole


6. How many moles are there in 24.0 grams of carbon?
2.0
2.2
2.22
2.3


7. How many grams are there in .50 moles of carbon dioxide, CO2?
22
222
202
2.2

2007-11-13 07:59:09 · 1 answers · asked by emando16 2 in Chemistry

What are some 2x2 Matrices that when multiplied by itself comes out to be ( 1 0)
( 0 1)
Please no 1's or 0's

2007-11-13 07:58:01 · 2 answers · asked by Evan L 2 in Mathematics

What I know:
vol of hydrogen peroxide sample is 8.72ml
mass of hydrogen peroxide sample is 8.72g
barometric pressure in lab is 764.29 mm HG
temp in lab is 21 celcius
vol of oxygen gas collected is 99.4 mL

1) How many moles of oxygen were collected
n= .0821 x 284 divided by 1atm x 99.4 mL
n=.23 moles

that doesnt seem right :(

2) using the balanced equation (there is twice as much h202 needed as o2 produced). What is the molarity of the hydrogen peroxide solution?
It would be double my answer in #1, but i dont think that answer is right

3) what is the mass percent hydrogen peroxide if the density is 1.00g/ml

4) calculate the volume of oxygen gas that would be produced upon the decomposition of 10ml of 30%(m/m) aqueous hydrogen peroxide solution. Assume the gas is collected at 1atm and 25 degrees celcius and density of hydrogen peroxide is 1.11g/mL.

2007-11-13 07:57:48 · 2 answers · asked by shirah d 2 in Chemistry

2007-11-13 07:43:41 · 6 answers · asked by Anonymous in Astronomy & Space

Need some help solving these tough Physics questions please....

Question 1
What is the Heat Capacity of a system consisting of a 0.475kg brass cup filled with 0.051kg of water?

Question 2
A container of nitrogen (N2)gas at 9.7oC contains 405 L at a pressure of 3.38 atm. If 27.4 kJ of heat are added to the container, what will be the new temperature?
I think you first determine the numberof moles.

2007-11-13 07:42:23 · 3 answers · asked by Anonymous in Physics

One of the examples in my notes states: Dr. D who has a mass of m=68kg easts a 300 Cal candy bar and then climbs 10 stories (Delta h= 35 meters) to his office. How many Calories has he burned?

so Work done = the change of PE (potential energy) = mgh= (68kg)(9.8 m/s^2) (35m) = 23300 J x (1Cal/ 4186 J)= 5.6 Cal

I understand the process of how they get 5.6 Cal but what I don't understand is why they used Word done= the change of PE? I thought Work was = the change of KE (kenetic engery)? isnt potential energy defined as stored energy associated w/position or configuration? or is the potential energy actually stored in Dr. D himself? and KE is derived from a veloctiy acting on a system?? please help explain this!!!

2007-11-13 07:41:35 · 2 answers · asked by Anonymous in Physics

Okay, so I want to know where I can find out what the lewis dot or vsepr model for the following molecules:

RnF2
SiI42- that's Silicon Iodide with a subscript 4 and then superscript 2-
KrO3
AlCl4-

Or if you know how to do the lewis dot structures, then that would be really great or if you can explain them to me would be just as good. thank you

2007-11-13 07:41:07 · 2 answers · asked by naknoi 5 in Chemistry

2007-11-13 07:39:12 · 2 answers · asked by RogerDodger 1 in Physics

The combination of an applied force and a
frictional force produces a constant torque of
25 Nm on a wheel rotating about a fixed
axis. The applied force acts for 7.8 s, during
which time the angular speed of the wheel
increases from 0 to 14 rad/s.
a) What is the moment of inertia of the
wheel? Answer in units of kg*m2.
b)The applied force is then removed, and the
wheel comes to rest in 77 s.
What is the frictional torque? Answer in Nm.
c)How many revolutions does the wheel make
during the entire 85 s interval? Answer in
units of rev.

O__o;; I have a midterm soon, and I'd appreciate it if someone could get back to me soon so I can study how to do this right! I don't know if what I have is even the right thing to start with. thanks!

2007-11-13 07:34:29 · 2 answers · asked by Venice Queen 2 in Physics

2007-11-13 07:30:34 · 1 answers · asked by leaudocean 1 in Chemistry

2007-11-13 07:28:23 · 15 answers · asked by lancashire lass 2 in Medicine

Question: AT 7a.m. the temperature was -15F. bY 1 p.m. the temperature had increased by 18F. What was the temperature at 1 p.m.?

2007-11-13 07:25:16 · 5 answers · asked by Anonymous in Mathematics